Publishing or printing houses typically utilize presses and the like which are capable of producing and processing signatures at high input rates. For example, the printing of newspapers which consists of printing various pages, interleaving the pages and folding the newspaper are all operations capable of being performed at high rates of speed. Once the individual pages or sheets forming the signature are interleaved and folded, the completed signatures are typically moved in a continuous stream at speed as high as 80,000 per hour whereupon the signatures, arranged in overlapping fashion with their folded edges forward and moving in the downstream direction, are typically delivered to a "mailroom" facility having a capability of stacking the signatures into bundles of a predetermined count (such as 50, 75, or 100 per bundle, for example), and then wrapping or tying each completed bundle, whereupon the bundles are delivered to trucks and the like for distribution thereof.
There exists a number of situations in which it is desirable to be able to remove one, a few, or a small or even large predetermined number of signatures from the delivery stream.
For example, it is typically desirable to be able to periodically remove one or two signatures from the delivery stream for examination as to print quality, neatness of folding and the like.
As another example, it may be desired to divert one, several, or even a large number of signatures away from the normal delivery stream for a variety of reasons such as, for example, that the first stacking location may have experienced a malfunction or in the event that the signatures are to be handled in alternating fashion by the first and second stacking assemblies in alternating fashion.
In addition to the above, it is frequently desired to remove paster copies interspersed with otherwise acceptable signatures so as to prevent the paster copies from being erroneously delivered to the stacking and bundling apparatus. Paster copies are the result of the pasting of the end of an exhausted paper roll to the beginning of a fresh paper roll during the printing operation, whereby the pasted ends form a poor quality signature.
The type of apparatus which is necessary to perform the above-defined objectives, i.e. that of extracting one, several or a large number of signatures from a delivery stream without otherwise affecting the normal delivery of the nonextracted signatures, must be capable of intercepting the delivery stream and diverting the signatures desired to be extracted from the stream to be removed from the delivery stream at an extremely high rate of speed so as not to divert any signatures which are to undergo normal delivery along the main or nondiverted delivery path.
One conventional apparatus for achieving this is described in copending application Ser. No. 398,072 filed Sept. 17, 1973, now U.S. Pat. No. 3,904,019.
In this apparatus, the signature stream is moved along a delivery path having a slight bend so that the spine of each signature is caused to be lifted a small predetermined distance away from the engaging top surface of the preceeding adjacent downstream signature to form a gap between the lifted spine and the top surface of the preceeding adjacent downstream signature. During normal operation, the signatures normally move over the bend in the delivery path and pass along delivery belts to the desired location which may, for example, be stacking and wrapping or tying apparatus, there being no interference with the delivery of signatures thereto. In order to extract one, several or a large number of signatures, a reciprocally movable shunting device comprised of a carriage supporting a pair of cooperating closed loop belt assemblies is moved substantially diagonally downward toward the region of the aforesaid bend in the normal delivery path so that the forward end, or nose, of one of said closed loop conveyor belt assemblies enters into the region of the gap formed between the folded edge, or spine, of a signature approaching the bend and the next adjacent downstream signature which has passed the bend in the normal delivery path by an amount sufficient to cause its spine and an intermediate portion of the downstream signature to assume a curvature following the delivery path. Thus the signature whose spine is just beginning to pass over the bend is diverted and is caused to move upwardly between the pair of cooperating conveyer belt assemblies until it is at least partially captured therebetween. As soon as the signature (or signatures) has (have) been captured between the cooperating conveyor belts, the reciprocating assembly moves upwardly at a rapid rate so that the movement of signatures between the cooperating conveyor belt assemblies, together with the diagonally upward movement of the conveyor belt assembly carriage causes the extracted signatures to rapidly move diagonally upward and away from the normal delivery path, allowing upstream signatures in the main path to continue their normal delivery path without any interruption whatsoever.
The major drawback in the above-mentioned structure resides in the fact that the assembly which reciprocally moves the pair of closed loop conveyor belt assemblies respectively into and out of the intercept position has a substantially large mass which, in the embodiment taught in the above-mentioned U.S. Pat. No. 3,904,019, is in excess of 100 pounds. Since the assembly is accelerated from a standstill position into the intercept position and is then abruptly moved from the intercept position to the withdrawn position, the large amount of mass which must be moved in order to accomplish the extraction operation for as few as one signature results in a necessarily sluggish apparatus which is incapable of performing extraction of as few as one signature from a stream of delivery signatures operating at very high rates of speed, or alternatively, one which requires extremely large driving forces.